python flask 连接mysql

from flask import Flask, render_template
from datetime import datetime
from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)
# MySQL所在的主机名
HOSTNAME = '127.0.0.1'
# MySQL监听端口号，默认3306
PORT = 3306
# 连接MySQL的用户名
USERNAME = 'root'
# 连接MySQL的密码
PASSWORD = '123456'
# MySQL上创建的数据库名称
DATABASE = 'flask_demo'
app.config[
    'SQLALCHEMY_DATABASE_URI'] = f'mysql+pymysql://{USERNAME}:{PASSWORD}@{HOSTNAME}:{PORT}/{DATABASE}?charset=utf8'
# 在app.config 中进行设置数据库的信息，然后使用sql创建一个db对象
# sqlalchemy会自动读取app.config中链接数据库的信息
db = SQLAlchemy(app)
#监测是否连接成功
with app.app_context():
    with db.engine.connect() as conn:
        rs = conn.execute(text("select 1"))
        print(rs.fetchone())